Update coursier to 2.1.21 #2352

Job	Run time
conformance	2m 3s
build (2_12, e2e)	3m 47s
build (2_12, test)	14m 2s
build (2_13, e2e)	4m 11s
build (2_13, test)	11m 11s
build (3, e2e)	4m 48s
build (3, test)	11m 13s
build (2_12, examples_and_formatting)	3m 0s
build (2_13, scala3_compat_test)	9m 0s
build (3, scala3_compat_test)	9m 25s
ci-passed	1s
	1h 12m 41s

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